1. Field of the Invention
This invention relates to a process for the manufacture of slide fasteners from an elongate stringer chain. More particularly, the invention is directed to a process for controlling the operation of each of the processing operating units installed serially in a slide fastener manufacturing plant.
2. Prior Art
There are known various control systems for effecting a controlled operation of respective processing units in a slide fastener production line during a substantially continuous cycle of operation. One such prior art process is disclosed for example in Japanese Laid-Open (Kokai) Publication No. 2-74205 for controlling the entire apparatus for making slide fastener products of different lengths, styles, sizes and/or colors. The arrangement of the apparatus is shown in FIG. 4 of the accompanying drawings in which a buffer W or storage device is provided between succeeding machines including a gapping machine P, a bottom stop fitting machine Q, a slider mounting machine R, a top stop fitting machine S and a cutting machine T, the maximum and minimum level of workpiece supply Y in the buffer W being a determining factor to continue or discontinue the operation of the respective upstream and downstream machines. The feeding of the workpiece or stringer chain W through the various machines relies upon the repetitive maximum and minimum levels of the workpiece W in each buffer W. This process therefore has a drawback in that the time required to complete each production cycle is prolonged, that the workpiece W is prone to become tainted or entangled while being stored in the buffers W, and that the workpiece W gets taut when its supply in each buffer W is depleted, resulting sometimes in defective slide fastener products.